The back box bolts are 9/16" heads about 4 inches long, dunno the thread size off the top of my head. Leg bolts are the same thread size, about 3 inches long, usually with 5/8" heads, although 9/16" heads will work...
You can get the exact size by contacting Pinball Resource (
www.pbresource.com) or you could just order a set from him. might even be able to get the leg bolts in black instead of steel.